Lubricating greases and method of making the same



Patented Dec. 7, 1948 LUBRICATING GREASES AND METHOD OF THE SAME Harold M. Fraser, New Orleans, La., assignor to International Lubricant Corporation, New rleans, La., a corporation of Louisiana No Drawing. Application August 27,1949, Serial No. 693,379

MAKING 1'7 Claims.

The present invention relates to the production of a lubricating grease containing an alkali metal soap of the saturated fatty acids, the metal component of the soap having an atomic weight varying between 6.99 and 22.99 together with an alkali metal acetate, the metal component of which has an atomic weight varying between 6.99 and 22.99, the alkali metal component of the acetate salt having the same atomic weight as the alkali component of the fatty acid soap, the latter preferably containing 14 to 24 carbon atoms per molecule. More specifically the invention relates to the production of a lubricating grease containing a sodium soap of a satuated fatty acid and sodium acetate or a lubricating grease containing a lithium soap of a fatty acid and lithium acetate. The sodium soap constituent of the grease may be made by saponifying fatty acids and preferably saturated fatty acids, or mixtures of fatty acids.

In one form of the invention a grease of the character set forth has present an alkali metal naphthenate as, for example, sodium naphthenate or lithium naphthenate. In this connection it is desired to point out that if sodium naphthenate is added to grease after it is made or formed in situ during the manufacture of the grease the final lubricating grease increases in hardness as the percentage of sodium naphthenate increases from about .5% to to said percentages being taken on the weight of the final grease. The preferred amount of the alkali naphthenate present in the grease to increase the hardness of the grease varies between 3% and 7%.

If the lubricating grease of the present invention contains an excess of a fatty acid as, for example .05% to 4% or somewhat in excess thereof, the alkali metal acetate content of'the grease may be as low as 2 /2% taken on the weight of the final grease and the grease will not be too soft, that is, it will have an ASTM worked penetration of about 260 and may be much higher as, for example, 310. While this is the preferred worked penetration, it may vary from this somewhat and still come within the spirit of the present invention as, for example, the worked penetration may be as'low as 190.

However, if the grease contains excess alkali as, for example, .02% to .8% or somewhat greater amount taken on the weight of the final grease,

' then the percentage of the sodium acetate presvaries from about 2 /270 to 12/.-% taken on the weight of the grease. pear to be obtained by using 6% of sodium acetate or lithium acetate when the grease contains free alkali in the amount set forth.

A lubricating grease containing an alkali metal soap of a saturated fatty acid or a mixture of fatty acids and an alkali metal acetate as, for example, sodium acetate or lithium acetate, and more specifically sodium saturated fatty acid soap and sodium acetate or a lithium fatty acid soap and a lithium acetate, exhibit a tendency to bleed or seep oil and further, the grease is rather soft.

This oil seepage is prevented or substantially inhibited by providing in the grease free saturated fatty acids in the percentages set forth, or when the lubricating grease contains an alkali metal soap as, for example, a sodium soap or lithium soap and also contains free alkali in the amount set forth, by having present as a component of the grease an alkali metal acetate in percentages ranging from about 5% to 7%, and preferably around 6%, the acetate salt being either a sodium soap or a lithium soap.

When the grease contains excess fatty acids or excess free alkali, the grease is made harder by having present in the grease about .05% to 15% of an alkali metal naphthenate and preferably 3% to 7% of the alkali metal naphthenate as, for example, sodium naphthenate or lithium naphthenate. That is, the worked penetration of the grease is brought to below 310.

An object of the present invention is to provide lubricating grease containing an alkali metal soap of the fatty acids or mixtures thereof, and an alkali-metal acetate, the metal component of the fatty acid soap having an atomic weight varying between about 6.99 and about 22.99, and the atomic weight of the alkali metal component of the acetate soap varying between about 6.99 and about 22.99, the soaps having the basic metal component.

, A further object of the present invention is to increase'the melting point of a lubricating grease containing an alkali metal soap of the fatty acids by incorporating in the grease an alakli metal acetate.

A further object of the present invention is to prevent oil seepage in a grease of the character herein set forth when'the' grease contains free alkali.

Another object of the present invention is to prevent seepage in a sodium soap grease of the character herein set forth when the greases contain free alkali by having presentat least about counteract in greases containing an alkali metal soap of the-fatty acids, excess fatty acids, and an alkali metal acetate, the tendency of the grease The optimum results apto become softer upon the incorporation in the grease of an alkali metal acetate, this being accomplished by having present in the grease a compound furnishing naphthenic acid radical as, for example, sodium naphthenate in a sodium soap grease, and lithium naphthenate in a lithium soap grease.

Another object of the present invention is to produce a lubricating grease of the character herein set forth in which a saponiflable base of the grease making batch is a fatty acid or a mixture of fatty acids, the batch also containing ingredients producing an alkali metal soap as, for example, a sodium soap or a lithium soap, said saponifiable organic base containing only a small amount of glyceride or being substantially en- Table I Per cent Total Soap, including sodium 17.5..... 15.8... 15.8.

acetate.

Per cent Sodium acetate 5.3 4.0.-.. 4.0. Per cent Sodium naphthenate nil .55.. .92. Melting point 'Ioo soft 425 F. 430 F. Per cent Free Fatty Acid 07 .25.-.. .30. Worked Penetrations 'Ioo soft. 264.... 240.

In general, when a grease contains a sodium soap of a fatty acid and a sodium acetate, or when the grease contains a lithium soap of a fatty acid and lithium acetate, and when the free fatty acid varies between about 0.02% to 0.3% or over as, for example, 0.02 to 0.8%, and the total soap content including thesodium acetate or the lithium acetate varies from about 8% to about 35%, the sodium acetate or the lithium acetate may vary from about 2 4% to about I2 and the balance of the soap content of the grease may be a sodium soapof a fatty acid or a lithium soap of a fatty acid. In a lubricating grease of this character, the grease may be made harder by adding from about .05% to 15% of an alkali metal naphthenate as, for example, sodium naphthenate or lithium naphthenate.

It is desired to point out that in a sodium soap grease, the use of a sodium acetate soap in the amount set forth only has an influence on preventing seepage of oil from the grease when the grease contains free alkali. The same holds true for a lithium soap grease of a fatty acid and lithium acetate. However, in a grease either containing free alkali or free fatty acid and 3% to 35% of an alkali metal soap of a fatty acid, the sodium naphthenate increases the hardness of the grease and decreases the tendency of the grease to bleed. In connection with the above, it is desired to point out that if sodium naphthenate is added to a lubricating grease containing a mineral oil base and 3% to 35% of sodium stearate the more sodium naphthenate that is added, the softer the grease becomes, but if the grease contains a sodium acetate, then the more sodium naphthenate added to the grease, the harder the grease becomes. This also holds true for a lubricating grease containing a mineral oil base or its equivalent or a grease contain g a mineral 011 base having a small percentage of other oils present when the grease contains a lithium soap of a fatty acid and lithium acetate. The following is an example illustrating the present information:

Example I 850' gms. hydrogenated fish fatty acids (50-53 titre), 50 gms. naphthenate acid, and 1200 gms. 100 coastal oil are heated in a kettle until the fatty acids are melted. Thereafter, 124 gms. of sodium hydroxide are dissolved in water and added to the kettle. Shortly thereafter a solution of 400 gms. of sodium acetate in water is added and the mass heated until the water is driven off. The sodium acetate may also be formed in the grease by adding to the grease acetic acid and sodium hydroxide. Thereafter 1400 gms. of 100 coastal oil and 3800 gms. of 2000 coastal red oil are slowly added. The temperature of the mixture is raised when all the oil has been added to about 390 F. and the melting product is poured into a pan in a layer approximately 4 inches thick. It is then cooled to room temperature in about 12 hours. If the grease is cooled in layers of about A" thick, the time of cooling is decreased but the cold grease is somewhat harder in consistency. The grease produced as above set forth when subjected to the roll test described in Patent 2,397,956 had a micro penetration of 128 before rolling, and after 142 hours of rolling had a micro penetration of 145. The usual grease containing a sodium soap of fatty acid or a mixture thereof, has afterrolling a micro penetration in excess of 200.

The following table shows the effect of sodium acetate in preventing oil seepage in a grease containing a sodium soap of a fatty acid, preferably having 14 to 24 carbon atoms in the molecule, said grease also containing sodium acetate, and an excess of alkali.

It is noted from the foregoing table that when the sodium acetate present in the grease approximates between 5% to 7%, the tendency of the grease containing free alkali to seep oil is greatly decreased and also the grease becomes slightly softer. V

The following table shows the effect of sodium acetate on the hardness of a grease containin a sodium soap of a fatty acid and sodium acetate, said grease containing excess free fatty acid.

Table III Per cent Total soap, including sodium acetate 17.4 16.9 16. 3 15.3 14. 3 Per cent Sodium acetate 5. 8 5. 2 4. 6 3. 2. 7 Per cent Sodium Naphthenate .0 9 9 9 9 Melting Point. .....degrees- 402 412 412 460 404 Worked Penetration 300 270 260 225 220 Per cent FreeFatty Acid 19 17 38 36 22 Oil Seepage None None None None None The following table shows the effect of using a glyceride in a grease containing sodium soap of a fatty acid and sodium acetate, said grease containing some glycerine:

Table IV Percent Total soap, including sodium 7 acetate 17. 2 2 Per cent Scan from glycerldes. 38 1.0 1.58 nil Per cent Glycerine added nil nil nil 1.0 Worked penetrations 218 230 282 345 high melting point can only be made using acetic acid, the grease containing acetic acid salts.

It is desired to point out that ordinary sodium soap lubricating greases containing a sodium soap The above table indicates that the use of the glycerine makes the grease softer.

The following is an additional example showing the production of a grease in accordance with the present invention using other low carbon I fatty acids:

The following is an additional example of grease compounded in accordance with the present invention', said grease containing free sodium hydroxide:

Eagample III Hydrogenated fish fatty acids, 54 titre gms 150 Palm oil gms Naphthenic acids gms 25 Lactic acid gms 40 Coastal pale oil, 100 vis. at 100 F' gms 700 Sodium hydroxide in solution gms 55 Coastal red oil, 2000 vis. at 100 F gms 800 Free sodium hydroxide percent .4 Melting point of grease F 332 The following example is directed to the production of a lithium soap grease containing lithium acetate:

' Example IV Hydrogenated fish fatty acids, 54 titre gms 150 Palm oil gms 25 Naphthenic acid -gms '25 Acetic acld gms 40 Coastal pale oil, 100 vis. at 100 F. gms 700 Lithium hydroxide in s01ution.- gms 80 Coastal red oil, 2000 vis. at 100 F gms 800 Worked penetration 322 Melting point of grease F 422 Appearance Smooth-opaque Micro penetration before rolling 166 Micro penetration after rolling 14 hours-.. 175 Grease very stable to mechanical working.

Example III clearly indicates that while greases can be made with salts of low molecular weight.

other than the salts of acetic acid, greasesof of a fatty acid-have in the past usually melted .belcw 400 F. and when heated above their melting point separated or leaked oil when cooled at room temperature. In accordance with the present invention a sodium soap grease, that is a sodium soap grease containing a sodium soap of a fatty acid, preferably having 14 to 24 carbon atoms per molecule, has its melting point raised to 400 to 470 F. or higher by incorporating in the greasea sodium acetate. If the grease contains excess fatty acids or, stated differently, free fatty acids, varying in amount from .02% to about .3% or .4% or even higher, then the new lubricating grease which has a-melting point varying between 400 F. and about 470 F. does not seep oil. However, if the grease containing the sodium acetate in the percentages hereinbefore set forth has free alkali present, varying from about .2% to .8 or more, then the grease does leak or separate oil w en cooled at room temperature unless there is about 5% of the sodium acetate or lithium acetate present in the sodium soap grease or the lithium soap grease. Therefore, in a sodium soap grease or a lithium soap grease which contains free alkali, in order to prevent oil-leakage there is a critical amount of alkali'acetate which it is necessary to have present, this critical range Statedbeing between about 5% to about 7%. somewhat differently, it is the 10 let limit which is critical in order to prevent bleeding or oil seepa e when the grease which has had added thereto sodium acetate if it is a sodium. acetate When, however, greases of the above character do not have free alkali but have free fatty acid, the amount of sodium acetate or lithium acetate added is not so critical but it may be as low as 2.5% to 5%better results being obtained at 4%, as shown in Table I.

The sodium soap-sodium acetate grease or the lithium soap-lithium acetate grease of the present invention is soluble in boiling water. As previously pointed out, these greases may have excess fatty acids or excess sodium hydroxide. When an excess of sodium hydroxide is used as hereinbefore specifically set forth, the grease is harder for the same soap content than it is when the similar grease contains excess fatty acids. The melting point is also slightly higher when the grease contains excess sodium hydroxide. When the grease contains excess fatty acids, it has a tendency when it contains sodium acetate to be rather soft. Therefore, even though the melting point of the grease has been increased it has a tendency to become soft, and this has been counteracted by adding naphthenic acid. The function of the naphthenic acid is to make the grease harder. However, the alkali soap of naphthenic acid which is indicated may be the sodium naphthenate or the lithium naphthenatewhen added to ordinary sodium stearate grease, causes the grease to become softer. cordance with the present invention when the sodium or lithium naphthenate is added to it However, in acsodium soap grease which contains sodium acetate, broadly or in the percentages herein set forth, the alkali naphthenate acts entirely differently, namely causes the grease to become harder.

The following table shows the effect of varying naphthenic acid concentration upon the hardness of the grease:

grease of this character may contain 1% to of naphthenic acid expressed as a sodium soap thereof.

In one form or! the invention there is provided a lubricating grease having a melting point varying between 390 F. and 470 F., said grease comprising an alkali soap of the fatty acid, the alkali component of the soap having an atomic weight Grease Grease Grease Grease Grease Grease #1 #2 #3 #4 #5 #6 H dro enated Fish OilFattyAclds 10.20%- 9.83 9.66 8.737--. 5.83%--. 2.93 NZphtlienicAcids 1.46%--. 1.83;... 2.20%.-. 2.93 5.839... 8.73 SodluinAcetete 4.107.-- 4.70%.-- 4.70 4.1 4.10 4.10 Sodium Hydroxide 1.1 a 1.10 1.70 1.10 v--. 1.107-- 1.767 500s. U. S. Vis. Coastal 0i1 8l.94 81.94%" 81.94 81.94%" 81.94 81.88 A. 8.1. M. Dropping Point,F 412... 412-.-" 413--. 434 403. 6". A. S. T. M. Worked Penetratiom. 220 252 240 225 240. Mechanical Stability by Roll Test Good Good" Good-- Fair Poor NotRun.

In carrying out the present invention, it is varying between 6.99 and about 22.99, the grease highly desirable that the sodium soap-sodium acetate grease or the lithium soap-lithium acetate grease be made from a grease forming batch in which the fatty acids are .the saponifiable constituent. A small amount of glyceride may be used but the grease becomes softer in direct proportion to the amount of glyceride used during the grease-making stage. The sodium soapsodium acetate grease or the lithium soap-lithium acetate grease made from a batch containing fatty acids is much firmer and will have a better appearance than if the soaps are made from a grease-making batch containing even a small proportion of glycerldes. I

In the present specification all temperatures are in degrees F., and all percentages are by weight taken on the weight of the grease batch.

The saponifiable component of the grease making batch may be any of the materials usually used in the production of grease. The fatty acids usually used in grease making are the saturated fatty acids containing 14 to 32 carbon atomsin a molecule and preferably 14 to 24 carbon atoms in a molecule. Any of the unsaturated fatty acids may be used which are usually used in the making of grease, said unsaturated fatty acids usually containing from 18 to 22 carbon atoms per molecule.

The oil constituent of the grease making batch used in carrying 'out the present invention is usually a mineral oil such as is well known in the art, but may be a vegetable oil or an animal oil or any fat usually used in the production of sodium soap greases or in the production of lithium lubricating grease.

Where in the specification the melting point is referred to, this is intended to denote the ASTM dropping point as obtained by ASTM procedure D566, the 1942 Year Book.

While the optimum amount of naphthenic acid added to the grease varies between 2% to 6% based on the weight of the grease batch, in the final grease the optimum percentage of the alkali naphthenate varies between 3% to and including 7%. Due to the low atomic weight of the alkali metals used, the percentage increase in the final grease of the alkali naphthenate is relatively little.

In accordance with the present invention there has been provided a lubricating grease containing a lubricating oil which is preferably, although not necessarily, a mineral oil and up to 25% of sodium stearate. The grease may contain 2%% to 12% of sodium acetate, said percentages be- I ing taken on the weightof the final grease. A

containing 2.5 to 12.5% of an alkali salt of acetic acid, the alkali component of the acid salt having the same atomic weight as the alkali component of the fatty acid, said percentages being taken on the weight of the final grease. A grease of this character may have from 3 to 7% of an alkali naphthenate present, said percentages being taken on the weight of the final grease. In the broadest form of the invention there may be present in a grease such as here set forth .05 to 15% of an alkali naphthenate. I

The invention also consists in the method of increasing the melting point of a sodium soap grease containing a lubricating oil base comprising incorporating in the grease 2.5% to 12.5% of sodium acetate, said percentages being taken on the weight, of the final grease, although in the preferred form of the invention there is incorporated in the grease 4% to 7% of sodium acetate, said percentages being taken on the weight of the final grease.

In one form of the invention a method is provided of increasing the melting point of a sodium soap grease containing a lubricating oil base and having a free alkali content varying between .2% to about .8%, while at the same time substantially inhibiting the seepage of oil from the grease by incorporating in the grease at least 5% of sodium acetate, said percentages being taken on the weight of the final grease. There mayalso be present in said grease at least .5% of an alkali naphthenate. The melting point of a lithium soap grease containing a mineral oil base or other oil base, and having a free alkali content varying between about .2% to about .8% may have its melting point increased and at the same time may be inhibited against seepage of the oil from the grease by incorporating in the grease at least .5% of lithium acetate. The lithium soap grease may have at least .5% of an alkali naphthenate incorporated in the grease, said percentages being taken on the weight of the final grease. 1,

The percentages set forth in all the claims are taken on the weight of the final grease.

In preparing the grease herein set forth, potassium or lithium naphthenate may be substituted for the sodium naphthenate in the same percentages as set forth for the sodium naphthenate. The sodium soap may have added thereto either a sodium naphthenate or apotassium naphthenate or a lithium naphthenate. The lithium soap may have added thereto a lithium naphthenate, potassium naphthenate or sodium naphthenate. The term "alkali naphthenate" as used herein is intended to cover sodium. potassium, or lithium naphthenate. I claim: a I

'1. A grease composition comprising a mineral lubricating oil and having incorporated therein in an amount suiiicient to thicken the mineral oil to a grease consistency, an alkali soap of a high molecular weight fatty acid, and 2.5% to 12.5% by weight of an alkali salt of acetic acid, the alkali components having an atomic weight varying between about 6.99 and about 22.99.

2. A grease composition comprising a mineral lubricating oil and having incorporated therein in an amount suflicient to thicken the mineral oil to a grease consistency, analkali soap of a high molecular weight fatty acid from about 2.5% to 12.5% by weight, alkali salt of acetic acid and 3% 'to 7% by weight of an alkali naphthenate, the alkali components having an atomic weight varying between about 6.99 and about 22.99.

3. A grease composition comprising a mineral lubricating oil and having incorporated therein in an amount suflicient to thicken the mineral oil to a grease consistency, an alkali soap of a high molecular weight fatty acid, from about 2.5% to 12.5% by weight alkali salt of acetic acid and 0.05% by weight of an alkali naphthenate. the alkali components having an atomic weight varying between about 6.99 and 22.99.

4. The method of increasing the melting point of a grease comprising a mineral oil and a sodium soap in an amount suflicient to thicken the mineral oil to a grease consistency, by incorporating in the grease 2.5% to 12.5% by weight of sodium acetate.

5. The method of increasing the melting point and preventing bleeding of a grease comprising a mineral lubricating oil and a sodium soap in an amount sufficient to thicken the mineral oil to a greas consistency, said grease having a free alkali content varying between about 0.2% to about 0.8%, by incorporating in the grease about 5.07 by weight of sodium acetate.

6. The method of increasing the hardness and the melting point of a grease comprising a mineral lubricating oil and a sodium soap in an amount suflicie'nt to thicken the mineral oil to a grease consistency, said grease having a freealkali content varying between 0.2% to about 0.8% by incorporating in the grease at least of sodium acetate and at least 0.5 of an alkali naphthenate.

7. The method of increasing the hardness and the melting point of a grease comprising a mineral lubricating oil and a lithium soap in an amount sufllcient to thicken the mineral oil to a grease consistency, said grease having a free alkali content varying between about 0.2% to about 0.8%, by incorporating in the grease at least 5% of lithium acetate and at least 0.5% of an alkali naphthenate.

8. The method of increasing the hardness and the melting point of a grease comprising a mineral lubricating oil and 'a lithium soap in an amount suflicient to thicken the mineral oil to a grease consistency, said grease having a free alkali conproportion is lithium soap of hydrogenated fish oil v tent varying between about 0.2% to about 0.8%

by incorporating in the grease at least 5% of lithium acetate.

9. The method of increasing the melting point and inhibiting bleeding of a grease comprising a mineral oil and an alkali soap of a high molecular weight fatty acid present in an amount suflicient to thicken the mineral oil to a grease consistency, said grease having a free alkali content varying between about 0.2% and about 0.8%, by incorporating in the grease atleast 5% by weight of an alkali salt of acetic acid, the alkali components having an atomic weight varying between about 6.99 and 22.99. a

10. The method of increasing the hardness and the melting point of a grease comprising a mineral oil and an alkali soap of a high molecular weight fatty acid present in an amount sufiicient to thicken the mineral oil to a grease consistency, said grease having a free alkali content varying between about 0.2% and about 0.8% by incorporating in the grease at least 5% by weight of an alkali salt of acetic acid, and 0.5% to 15% by weight of an alkali soap of naphthenic acid, the alkali components having an atomic weight varying between about 6.99 and 22.99.

11. The method of increasing the hardness of a lubricating grease containing a lubricating oil base, about 3.0% to 25.0% of sodium soap of a fatty acid, and about 2.5% to about 12.5% of sodium acetate comprising incorporating in the grease from 5% to 15% of an alkali soap of naphthenic acid, said percentages being taken on the weight of the tin l grease.

12. The metho of increasing the hardness of a lubricating grease having a lubricating oil base, about 3% to about 25% of sodium soap of a fatty acid having 14 to 24 carbon atoms in each molecule, and about 2.5% to 12.5% of a sodium acetate salt comprising incorporating in a grease about .5% to about 15% of an alkali soap of naphthenic acid, said percentages being taken on the weight of the final grease.

13. The method of increasing the melting point of a grease comprising a mineral oil and a sodium soap having a free alkali in an amount suilicient to thicken said mineral oil to a grease consistency by incorporating in the grease about 5% by weight sodium acetate.

14. A lubricating grease composition comprising a lubricating oil base and containing alkali metal 'compounds totaling from about 8% to about 35% by weight, of which from about 2.5% to about 12.5% is sodium acetate, the balance being sodium stearate and the percentages being selected such that the major proportion is sodium stearate.

15. A lubricating grease composition comprising a lubricating oil base and containing alkali metal compound totaling from about 8% to about 35% by weight of which from about 2.5% to about 12.5% is sodium acetate, 1.0 to 15% is sodium naphthenate, the balance being sodium stearate and the percentages being selected such that the major proportion is sodium stearate.

16. A lubricating grease composition comprising a lubricating oil base and containing alkali metal compounds totaling from about 8% to about 35% by weight, of which from about 2.5% to about 12.5 is lithium acetate, the balance being lithium soap of hydrogenated fish oil fatty acids and the percentages being selected such that the major fatty acids,

17. A lubricating grease composition comprising a lubricating oil base and containing alkali.

, major proportion is lithium stearate.

HAROLD M. FRASEl't.v

(References on following page) REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS flumber Name Date Carmichael et a1. Apr. 16, 1940 Zimmer et a1. Dec. 9, 1941 Number 

